The present invention generally relates to a valve assembly. More specifically, the present invention relates to a flapper valve with a valve restraint on a valve plate for a piston compressor.
Typically, a valve plate is attached to a compressor cylinder block and has intake and discharge ports to the cylinder. The intake valve is mounted on the underside of the valve plate while the discharge valve is located on the top surface of the valve plate.
Reed valves are generally used to regulate intake and discharge port openings in alternative fashion where each port requires a separate valve. The reed valves are generally made of thin, resilient metal leaves and are held in place in a cantilever fashion by rivets, small screws, or by other suitable clamping means.
A reed valve assembly is known from U.S. Pat. No. 4,437,490 in which the reed valve arrangement has a base formed by two rigid members between which an intermediate portion of the reed is sandwiched. One of the rigid members has a downstream facing seat for the intake port while the other of the rigid members has a downstream facing seat for the discharge port. This arrangement allows for a single reed to be utilized wherein one free end thereof acts as an intake valve member while the other free end serves as a discharge valve member.
Material requirements for the above-mentioned arrangement are extensive since two valve plates are used with the reed member sandwiched between the two base members. The recesses of the base member must then be manufactured in complimentary fashion in order for the reed to flex freely within the recess.
Also known from commonly assigned U.S. patent application Ser. No. 07/889,254 filed May 26, 1992, now issued as U.S. Pat. No. 5,213,125 to Leu is a valve plate having a flapper valve and a valve restraint mounted in a recess of the valve plate. The valve restraint prevents the flapper valve from moving outside of the recess so that it does not come in contact with, for example, a piston in a compressor cylinder. The restraint also provides better valve efficiency and lowers the stresses on the flapper valve. The recess in the valve plate provides for an error proof assembly of the flapper valve and the restraint in the valve plate. It is thereby insured that the flapper valve has its inherently curved surface pressed against the valve plate.
Guides are provided in the recess to eliminate the need for additional fixtures to position the flapper valve and valve restraint over the port in the valve plate. Furthermore, recessed intake ports eliminate the need for a screw clearance recess in the piston top and also allow any 90.degree. orientation of the valve plate and head.
Furthermore, the exhaust recess reduces clearance volume to offset the increase caused by the intake recess. The exhaust recess allows for the addition of sound-reducing/filtering material or baffles in the head without interfering with the valve movement and sealing. The valve plate assembly including flapper valve and valve restraint of Leu, however, has the drawback that the valve restraint typically adheres to the flapper valve when in use. As a result, the flapper valve may stick to the underside of the restraint and may not return to the sealed position.
Therefore, a need exists for an improved valve restraint for use with a valve plate having a flapper valve to overcome the deficiency of the prior art systems.